Climate change may have increased frequency of earthquakes in Himalayas, says Minister of Earth Sciences
Climate change may have marginally increased the frequency of earthquakes in the Himalayas though there is no reliable system of forecasting them, Jitendra Singh, Minister of Earth Sciences (MoES) said in response to multiple queries in the Lok Sabha on Wednesday.
The melting of thick ice sheets, due to climate change, could reduce load on the earth’s crust and this could cause “micro-level earthquakes” (or those with a magnitude less than 3), Mr. Singh said in response to a query by MP Badruddin Ajmal on whether “frequent earthquakes have been striking various areas in the country, specially the capital city of Delhi and adjoining areas as well as northeastern States and hill-States, during the last few years.”
Small earthquakes are far more frequent than large ones and pass by undetected by the sensors deployed. The National Centre for Seismology (NCS), an MoES body that tracks seismic activity globally, has reported two quakes on Thursday alone in Manipur and Uttarkashi, Uttarakhand — both below 4 on the scale.
Previous work by seismologist Jean-Philippe Avouac at the California Institute of Technology, United States has linked such micro-seismicity to the monsoon cycle in India. During monsoon months, precipitation on the Indo-Gangetic Plain increased stress loads on Earth’s crust there and decreased micro-seismicity in the Himalayas. During the dry winter, the reduced weight from water increased such micro-seismic tremors.
While earthquakes are largely linked to tectonic activity, there is emerging consensus among scientists that warming and climate change after-effects can generate tipping points that may trigger an already unstable, deep geological faultline into releasing pent up sub-surface strain as an earthquake.
“Presently, no proven system exists in the country to provide the early warning of earthquakes. Also, there is no scientific technique available anywhere in the world to predict an earthquake precisely in terms of time, location and its magnitude. However, NCS is planning to install Earthquake Early Warning systems in the targeted areas, initially in the Himalayas as a pilot project,” said Mr. Singh in response to a separate joint query from members Shardaben Patel and Mitesh Patel.
The government had taken steps to better prepare against earthquake tremors, the Minister said. Seismic microzonation work of the Delhi National Capital Region was carried out on 1:10000 scale and this report was made available to the Bureau of Indian Standards (BIS) to revise the present Building Design code into an ‘earthquake risk resilient code’ for structures and buildings in NCT-Delhi. “There is a need for retrofitting of older buildings and the same is being adopted by the Delhi Development and Management Authority (DDMA) and State governments for enhancing resilience,” his reply added.
About 59% of the land mass of India is prone to earthquakes of different intensities. As per the seismic zoning map of the country, the entire country is classified into four seismic zones. Zone V is seismically the most active region, while zone II is the least. Approximately, 11% area of the country falls in zone V, 18% in zone IV, 30% in zone III and the remaining in zone II.
Parts of Jammu and Kashmir (Kashmir valley), the western part of Himachal Pradesh, the eastern part of Uttarakhand, Rann of Kutch in Gujarat, part of northern Bihar, all the northeastern states and Andaman & Nicobar Islands come under zone V.
Zone IV includes the remaining parts of Jammu & Kashmir, Ladakh, the remaining parts of Himachal Pradesh and Uttarakhand, some parts of Haryana, Punjab, Delhi, Sikkim, the northern part of Uttar Pradesh, parts of Bihar, West Bengal, Gujarat and Maharashtra, and western Rajasthan.